A mobile robot refers to a robot that may run autonomously or by external control, and performs specific tasks, and there are a cleaning robot, a monitoring robot, and the like in accordance with tasks to be performed. The mobile robot generally has a function capable of autonomously performing assigned tasks, for example, cleaning work or monitoring work.
When describing a cleaning mobile robot as an example, the cleaning mobile robot autonomously moves in a predetermined cleaning zone such as a house or an office, and sucks dust or foreign substances. To this end, in addition to a configuration of a general vacuum cleaner that sucks dust or foreign substances, the mobile robot includes a wheel assembly which allows a robot to run, a plurality of sensing sensors which senses obstacles so that the robot may run without colliding with various obstacles in the cleaning zone, a battery which supplies electric power, a microprocessor which controls the entire apparatus, and the like.
The wheel assembly, which allows the mobile robot to run, includes a wheel, and a power source such as a driving motor that provides driving power to the wheel. The wheel is rotated by driving power provided from the power source such that the mobile robot may move. However, the wheel is generally configured to be rotated in a fixed state with respect to a robot body of the mobile robot. However, the mobile robot does not run only on a flat running surface, but may run on a non-uniform running surface such as an uneven running surface, may pass over an obstacle such as a threshold, and may run on a slippery running surface.
When the mobile robot runs on an uneven running surface, because of the non-uniform running surface, only the wheel positioned at one side comes into contact with the running surface, but the wheel positioned at the other side is positioned at a concavely depressed region, and is not in contact with the running surface, and as a result, the mobile robot is continuously rotated at the same position about an axis that is defined by the wheel that is not in contact with the running surface. That is, there is a problem in that the mobile robot does not move forward, but is continuously rotated at one position.
In addition, in a case in which the mobile robot passes over an obstacle such as a threshold, when a height of the obstacle is greater than a height by which the wheel protrudes from the robot body, the wheel does not come into contact with the running surface, and thereby, a lower end of the robot body is caught by the obstacle such that the mobile robot may not move forward or rearward.
In addition, contact force of the wheel is decreased at a slippery running surface having a small frictional force because frictional force, which acts between the running surface and the wheel, is small, and thereby, there are problems in that loss of driving power may occur, and the mobile robot may not run in an intended direction.
In addition, since the wheel is mounted in a fixed state with respect to the robot body, impact or vibration, which occurs at the wheel from the running surface when the mobile robot runs while passing over an obstacle such as a threshold, or runs on an uneven running surface, is transmitted as it is to the robot body. Components such as sensors, which are sensitive to impact, are mounted in the mobile robot, and the sensors and the like may be abnormally operated due to vibration transmitted from the wheel, such that malfunction of the mobile robot may occur, and an operation of the mobile robot may stop in a serious case.
In addition, there is a need for the wheel assembly of the mobile robot that may be easily assembled when the wheel assembly of the mobile robot is assembled to the robot body of the mobile robot.